Hot Ocean Vents Possible Source of Life on Earth

If it weren't for the emergence of complex organic molecules some billions of years ago, humans as well as other organisms wouldn't exist today. Now new research claims that hot ocean vents found on the seafloor are the source of life on Earth as we know it.

According to a team of chemists from the University College London (UCL), the surfaces of mineral particles inside hydrothermal vents have similar chemical properties to enzymes - the biological molecules that drive chemical reactions in living organisms. This means that seabed vents are able to create simple carbon-based molecules, such as methanol and formic acid, out of the dissolved carbon dioxide (CO2) in the water.

The discovery, published in the journal Chemical Communications, suggests that some of the key building blocks for organic chemistry were already being formed in nature before life emerged. Thus, hot vents on the seabed could have spontaneously produced the organic molecules necessary for life as we know it.

"There is a lot of speculation that hydrothermal vents could be the location where life on Earth began," researcher Nora de Leeuw, who led the UCL team, said in a press release. "There is a lot of CO2 dissolved in the water, which could provide the carbon that the chemistry of living organisms is based on, and there is plenty of energy, because the water is hot and turbulent. What our research proves is that these vents also have the chemical properties that encourage these molecules to recombine into molecules usually associated with living organisms."

What's more, the findings also have potential practical applications. For example, products such as plastics and fuels could possibly be synthesized from CO2 rather than oil.

It is widely believed that life on Earth first flourished about two billion years ago, but this and other research suggests that living organisms actually emerged earlier than scientists previously thought. And now it seems that hydrothermal vents may have played a role in that. (Scroll to read on...)

To find out, the researchers conducted a series of lab experiments and also used supercomputer simulations. This way they could better determine the conditions under which the mineral particles would catalyze the conversion of CO2 into organic molecules. The experiments replicated the conditions present in deep sea vents, where hot and slightly alkaline water rich in dissolved CO2 passes over the mineral greigite (Fe3S4), located on the inside surfaces of the vents.

The simulations, which were run on UCL's Legion supercomputer, provided a molecule-by-molecule view of how the CO2 and greigite interacted during the experiments.

"We found that the surfaces and crystal structures inside these vents act as catalysts, encouraging chemical changes in the material that settles on them," explained study co-author Nathan Hollingsworth. "They behave much like enzymes do in living organisms, breaking down the bonds between carbon and oxygen atoms. This lets them combine with water to produce formic acid, acetic acid, methanol and pyruvic acid. Once you have simple carbon-based chemicals such as these, it opens the door to more complex carbon-based chemistry."

According to conventional theories, either a spark from a lightning bolt, interstellar dust, or an underwater volcano triggered the very first life on Earth. But these events alone were not enough to sustain life. Other theories suggest that increasingly complex carbon-based chemistry led to self-replicating molecules - and, eventually, the appearance of the first cellular life forms.

Now that researchers have shown that simple organic molecules can form in nature without the presence of living organisms, it means that hydrothermal vents may be the origins of life.

Aside from this discovery, the research is also important in that it could have practical applications. It provides a method for creating carbon-based chemicals out of CO2 - without the need for extreme heat or pressure. This could, in the long term, replace oil as the raw material for products such as plastics, fertilizers, and fuels.

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